Control knob assembly

ABSTRACT

A CONTROL KNOB ASSEMBLY IS DISCLOSED WHEREIN ROTATIONAL MOVEMENT OF THE CONTROL KNOB EFFECTS RADIAL MOVEMENT OF A COOPERATING INDICATOR. THE KNOB IS PROVIDED WITH A SPIRAL CHANNEL IN ITS UNDERSURFACE FOR RECEIVING A LEG OF THE L-SHAPED INDICATOR. THE LONGER LEG OF THE INDICATOR EXTENDS RADIALLY OUTWARD FROM THE CONTROL KNOB AXIS THROUGH A SLOT IN THE ASSEMBLY HOUSING. HOOKS INTEGRAL WITH THE HOUSING ARE ADAPTED TO GRIP A PERIPHERAL FLANGE ON THE KNOB TO RETAIN THE DIALED POSITION. AT LEAST ONE OF THE HOOKS IS PROVIDED WITH A CONVEX DIMPLE WHICH COOPERATES WITH CORRESPONDING CONCAVE DIMPLES ABOUT THE PERIPHERY OF THE KNOB TO PROVIDE A &#34;CLICK&#34; INDICATIVE OF AN INCREMENTAL CHANGE IN THE CONTROL KNOB SETTING. THE KNOB IS FURTHER PROVIDED WITH A SPLINE OR KEYWAY ARRANGEMENT WHICH ACCOMMODATES AXIAL MOVEMENT OF THE STEM.

March 1971 w. D. RATTAN 3,572,284

CONTROL KNOB ASSEMBLY Filed Dec. 15, 1969 FIG. 3

INVENTOR, William D. Rofion BY %#.M

ATTORNEY I 3 &

United States Patent O 3,572,284 CONTROL KNOB ASSEMBLY William D. Rattan, Paramount, Calif., assignor to Robertshaw Controls Company, Richmond, Va. Filed Dec. 15, 1969, Ser. No. 884,809 Int. Cl. G09f 9/ U.S. Cl. 116-124 Claims ABSTRACT OF THE DISCLOSURE A control knob assembly is disclosed wherein rotational movement of the control knob elfects radial movement of a cooperating indicator. The knob is provided with a spiral channel in its undersurface for receiving a leg of the L-shaped indicator. The longer leg of the indicator extends radially outward .from the control knob axis through a slot in the assembly housing. Hooks integral with the housing are adapted to grip a peripheral fiange on the knob to retain the dialed position. At least one of the hooks is provided with a convex dimple which cooperates with corresponding concave dimples about the periphery of the knob to provide a "click indicative of an incremental change in the control knob setting. The knob is further provided with a spline or keyway arrangement which accommodates axial movement of the stem.

BACKGROUND OF THE INVENTION Field of the invention This invention generally relates to control knobs, and more particularly, to a combined control knob and indicator assembly which is capable of ndicating the complete range of control settings which is effected by several turns of the control knob.

Description of the prior art Many control devices, such as valves and the like, require considerably more than a simple 360 rotation to atlect a change from full off to full on. An example of such a control device is a thermostatic mixing valve used in water heaters. In a valve of this sort, several turns of the dial are necessary to include the entire range of temperature settings on the top surface of the dial. Pulley and string arrangements are generally not suitable to control environments. Gears are costly to manufacture and involve complicated assembly Operations.

SUMMARY OF THE INVENTION It is, therefore, an object of the present invention to provide a control knob assembly which produces a relatively minor indicator movement in response to several turns of the control knob.

It is another object of this invention to provide a control knob and indicator assembly for applications where multiple rotation is required for a gven range of adjustment.

It is a further object of the subject invention to provide a control knob assembly which is characterized by its simplicity of Construction and assembly and its low cost of manufacture.

According to the present invention, the foregoing and other objects are attained by providing a three-piece control knob assembly including a control knob, an indicator and a housing or cover, all of which may be made of inexpensive materials such as plastics and pot metal. The control knob has a spiral channel in its undersurface which receives a leg of the L-shaped indicator. The longer leg of the indicator extends radially outward from the control knob axis through a slot in the housing. The arrangement is such that rotational movement of the control knob effects radial movement of the indicator.

3572284 Patented Mar. 23, 1971 BRIEF DESCRIPTION OF THE DRAWINGS The specific nature of the invention, as well as other objects, aspects, uses and advantages thereof, will clearly appear from the following decription and from the accompanving drawing, in which:

FIG. l is a pictorial view of the control knob assembly according to the invention as it would appear mounted on a thermostatic mixing valve.

FIG. 2 is an enlarged plan view, partially broken away, of the control knob assembly illustrating the details of its unique construction.

FIG. 3 is a cross-sectional view of the control knob assembly taken along section lines 3-3 in FIG. 2.

FIG. 4 is a cross-sectional view taken along section lines 4-4 in FIG. 2 illustrating a hook having a convex dimple cooperating with a concave dimple in the control knob.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing wherein like reference numerals designate identical or corresponding parts throughout the several views, FIG. 1 shows the general appearance of the control knob assembly mounted on a thermostatic mixing valve or similar control devce generally indicated at 10. Obviously, the control knob assembly may be used with any multiple rotation control device, and other uses and applications will suggest themselves to those skilled in the art as the description proceeds. The reference to a mixing valve is, therefore, merely by way of illustration and not intended in any way to be limiting.

The control knob assembly includes three basic parts: the control knob 11, the indicator 12 and the housing or cover 13. The housing 13 is provided with a slot through which the indicator 12 may be viewed. Holes are appropriately provided in the housing 13 for mounting the assembly to the miixng valve 10 by means of screws 14. The indicator 12 has an index 15 integral therewith which cooperates with a scale 16 on either side of the slot in housing 13 to indicate the dialed setting. The index 15 may be scribed on the indicator 12 but is preferably molded on the surface thereof and projects a short distance outwardly therefrom. In a similar manner, the cooperating scale 16 on housing 13 may be scribed or otherwise marked on the surface but, again, is preferably molded or cast on the surface projectng a short distance outwardly therefrom. Molding is preferred since it eliminates the extra step of scribing or marking that would otherwise be required in the manufacture of the assembly.

FIGS. 2 and 3 show in more detail the control knob assembly. Knob 11 has a spiral channel 17 which may be either cut or molded in its undersurface, the latter being preferred. Channel 17 receives one leg 18 of indicator 12 which is adapted to move therein in a sliding manner. The action between the channel 17 and leg 18 of indicator 12 is much the same as the interaction between a cam and its follower. As knob 11 is rotated clockwise, indicator 12 is moved away from the center of the knob by the ever increasing, radius of channel 17. In the case of the thermostatic mixing valve referred to above,

the lead of the spiral channel 17 is such that the indicated temperature setting is calibrated With the increased or decreased outlet water temperature caused 'by rotation of the knob 11. The curvature of the cam-follower portion 18 of indicator 12 must be such as to he compatible with the changing radius of the spiral channel 17. Deending on the strength of the materials of which the assembly is constructed, a cylindrical cam-follower would sufiice. The extension 19 of the longer leg of indicator 12 slides into a recess 20 of housing 13. This extension 19 serves to constrain and support the indicator 12 throughout its radial travel.

As may be appreciated from the description thus far, the three pieces of the control knob assembly are uniquely adapted to manufacture by means of molding or casting. For example, the knob 11 and indicator may both be molded in a suitable plastic. While the housing 13 could also be molded in plastc, it is more desirably cast in pot metal or similar alloy.

Returning to the description of FIGS. 2 and 3, knob 11 has a splne or keyway arrangement in its central bore 21 which receives the splined or grooved shaft 22 of the control device. The shaft 22 is thus interlocked with knob 11 for rotational movement, but is free to move axially as indicated by the double-headed arrow on the shaft in FIG. 3. This is an important feature in thermostatic devices, for example, where the shaft 22 may be axially displaced by the thermal element.

The control knob 11 is held down by two hooks 23 and 24 integrally cast with housing 13. The two hooks 23 and 24 are located 180 apart on a diameter of control knob 11 and grip a flange 25 on the periphery of the knob. Hook 23 has a convex hemispherical dimple 26 on its innermost surface. This dimple 26 corresponds to and cooperates with three concave dimples 27 about the periphery of knob 11 just above flange 25. This is most clearly shown in FIG. 4. The concave dimples are located 120 apart. Making reference to the application to a thermostatic mixing valve again, one complete revolution of the control knob 11 causes a temperature increase or decrease of, say, l F. Thus, each click' of the knob as it is rota-ted indicates a temperature increase or decrease of 5 F. Clearly, other arrangements and combinations are possible. For example, hook 24 could also be provided With a convex dimple, and more or less concave dimples could be provided in knob 11. It is preferahle, of course, that the concave dimples be made in the more resilient material of the knob 11 and the con- 'vex dimple -be made in the harder material of the housing 13 for purposes of wear.

Inasmuch as the present inventon s subject to many variations, modifications and changes in detail, it is intended that all matter contained in the foregoing description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. A control knob assembly comprising:

a control knob having a spiral channel in its undersurface,

an L-shaped indicator having its shorter leg slidably disposed within said spiral channel and its longer leg extending radially outward from the central axis of said control knob, and

a housing for retaining said control knob and having a slot through which said indicator is viewed and further having a recess extending beyond said slot to receive the end of the longer leg of said indicator and thereby constrain and support said indicator throughout its entire length of radial travel.

2. A control knob assembly as recited in claim 1 wherein said control knob has a ange about its periphery and said housing is provided with at least two hooks integral therewith to grip said flange to retain the dialed position of said control knob.

3. A control knob assembly as recited in claim 2 wherein a plurality of concave dimples are provided about the periphery of said control knob and at least one of said hooks is provided With a convex dimple which corresponds to and cooperates With said plurality of concave dimples to produce a "click indicative of an incremental change in the setting of said control knob as it is rotated.

4. A control knob assembly as recited in claim 1 wherein said indicator has an index which cooperates with a corresponding scale adjacent the slot in said housing to indicate the setting of said control knob.

5. A control knob assembly as recited in claim 1 wherein said control knob has a central bore which is splined to receive a -grooved shaft of a control device thereby nterlocking the shaft with said control knob and restricting the rotational motion of the shaft to that imparted by said control knob While at the same time permitting the shatt to move freely axially.

References Cited UNITED STATES PATENTS 1,450,919 4/1923 Harris 116-129UX 2,400,55 3 5 1946 Howard 116-124 2,712,584 7/1955 Pantages 116-129UX 3,257,606 6/1966 Grant 116-129X F OREIGN PATENTS 199`,714 11/ 1938 Switzerland 116-129 LOUIS J. CAPOZI, Primary Examiner U.S. CI. X.R. 74-553; 116-133 

